The incident happened shortly after 7 a.m. ET and “weapons were discharged in the course of the incident, which remained under investigation at this time,” NSA spokesman Tommy Groves said in a statement.

“The situation is under control and there is no ongoing security or safety threat,” Groves added. “The FBI is presently leading the investigation.”

Three men, including the driver, were inside the unauthorized vehicle at the time of the incident, and investigators believe the car was a rental, according to Gordon Johnson, special agent in charge of the FBI’s Baltimore field Office. The FBI is investigating why shots were fired, Johnson said, but preliminary information indicates the gunfire was directed at the vehicle.

“That’s part of the investigation, to determine exactly what happened here,” Johnson said at a news conference Wednesday afternoon. “This vehicle did come onto the NSA compound unauthorized and NSA has a series of protocols that they respond to these types of events, so that is part of our investigation and one of the questions we’re trying to answer.”

NSA police took three people into custody, Groves said, adding that the incident is not terrorism-related.

The driver of the car, an NSA police officer and a civilian onlooker were injured during the incident and transported to a local hospital, according to Johnson. While he didn’t know the status of the wounded driver, Johnson said the injuries sustained by the officer and the civilian were described as not life-threatening.

Groves, the NSA spokesman, said earlier that preliminary reports indicate the injuries were not from gunfire.

Sources told ABC News the injuries were vehicle-related.

An earlier statement from the NSA said the incident took place “at one of NSA’s secure vehicle entry gates.”

FBI agents responded to the scene, working in collaboration with NSA police, sources told ABC News.